Pseudo-first Order Kinetic Model Research Articles

Hydrothermal synthesis of Ce2Sn2O7 nanoparticles for effective sonocatalytic performance

The Ce2Sn2O7 nanoparticles were successfully synthesized using a simple hydrothermal method. The crystal structure, morphology, and optical property of Ce2Sn2O7 nanoparticles were analyzed by X-ray diffraction patterns, scanning electron microscopy, transmission electron microscopy and UV–visible diffuse reflectance spectroscopy. The nanomaterial was first applied to ultrasonic catalytic degradation. The sonocatalytic activity of Ce2Sn2O7 nanoparticles was evaluated at room temperature and in the dark by using the Methyl Orange (MO) as the simulated contaminant. The effects of ultrasonic output power, Ce2Sn2O7 addition amount, initial concentration of pollutants, pH of solution, types of organic dyes and other factors on the catalytic degradation efficiency were investigated. The experiment results show that the ultrasonic catalytic degradation reaction of MO by the Ce2Sn2O7 nanoparticles basically follows the pseudo first-order kinetic model. Under the best conditions, the ultrasonic catalytic degradation rate of Methyl Orange reaches 97.8%, and the degradation rate can still reach 82.6% after four cycles of experiments. These results indicate that Ce2Sn2O7 nanoparticles can be used as acoustic catalyst for the purification of organic wastewater, which has a good application prospect.

Impact of Adsorption of Rare-Earth Elements on the Structure and Magnetic Parameters of Nanostructured Ceramic Oxides Containing Mg Nano Spinel Ferrite

This study focuses on the characterization and synthesis of ceramic materials that have magnetic nanoparticles (MgFe2O4) within an insulating (wüstite or magnesiowüstite) matrix (Mg1-xFexO). Ceramic Oxides were employed to absorb and elute rare-earth elements (REEs). Elements were carried out in experimental batches, including the effect of pH, adsorbent dose initial REE ions concentration, and equilibrium time. The Langmuir isotherm with a monolayer adsorption capacity surpassed 397 mg g−1 at room temperature. REE ions were effectively eluted from loaded Ceramic Oxides nanoparticles with 0.1 mol l−1 of HCl acid with an efficiency of 98%. Equilibrium modeling presented the Freundlich isotherm as the best fit model for both adsorbents and metal ions, indicating heterogeneity of the surface binding sites during adsorption. The pseudo-first order kinetic model was the best-fit model. Different qualitative techniques are used to emphasis the adsorption of REE ions onto Ceramic Oxides nanoparticles. The effect of REEs ions adsorption on the structural and morphological properties have been investigated using X-ray diffraction (XRD), porosity & surface area scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDX). The functional groups were detected by Fourier Transform infrared spectroscopy (FTIR). By applying a magnetic field of ±20 kOe, using vibrating sample magnetometer (VSM), (M-H) hysteresis loops were formed. The difference in ionic radius and atomic weight of the REE ions is highly renovated to the fluctuations in crystallographic and magnetic parameters. Finally, Ceramic Oxides nanoparticles possessed good adsorption properties such as stability and reusability, which have potential application in wastewater treatment.

Adsorption of diclofenac onto Fe2O3-pillared montmorillonite: Equilibrium, kinetics and thermodynamic studies

The kinetic regularities and thermodynamics of adsorption of one of the most common pharmaceutical pollutants diclofenac (DCF) on Fe2O3-pillared montmorillonites (Fe-PMts) have been first studied. Fe-PMts were synthesized by intercalation of natural montmorillonite with iron polyoxocations, followed by heat treatment at 623 and 723 K. The structural and textural characteristics have been studied by XRD, IR, SEM and low temperature N2 adsorption. It has been established that the pillaring lead to an increase in the specific surface of the natural clay by 2.4 times and an increase in the sorption capacity with respect to DCF up to 80 times. The main physicochemical parameters affecting the DCF adsorption were the pH, sorbent content, DCF concentration, and temperature. The specific DCF adsorption increased with decreasing pH, sorbent content, temperature, and with an increase in the initial DCF concentration. An analysis of the kinetic data and the adsorption isotherm was carried out using pseudo-first and pseudo-second order kinetic models, intraparticle diffusion model, and Langmuir and Freundlich adsorption models. The kinetic data of DCF adsorption were in agreement with the pseudo-second order kinetics model, and the adsorption isotherm was in good agreement with the Langmuir model with maximum adsorption capacity of 103.1 mg·g−1 at pH 5.9. DCF adsorption on Fe-PMt was a spontaneous and exothermic process based on the values of the thermodynamic parameters. The results of the study showed that Fe-PMt was an effective sorbent for removing DCF from aqueous solutions and could be used in pharmaceutical wastewater treatment as a cheap and environmentally friendly sorbent.

Oil Removal from Polluted Seawater using Carbon Avocado Peel as Bio-Absorbent

Oil spills are a very dangerous occurrence for the marine ecosystem as the marine life-form's existence gets unnecessarily threatened. Since the exploration of oil from marine resources has become a must and oil spills end up occurring accidentally, as a result, it becomes important to employ various oil spill cleanup methods. The purpose of the current work was to evaluate the oil sorption capacity of dried carbonized avocado peel (AP) waste. AP was dried under the sun and microwaved to have the activated carbon AP. In this study, batch adsorption studies were conducted to remove different oil types (Crude oil, Diesel, Kerosene, and Gas oil) from polluted seawater using AP. The effect of various important parameters, namely, mixing time, adsorbent dose, oil dose, oil types, and reusability on the oil uptake, and their optimum conditions for maximum sorption efficiency was studied. Batch studies indicated that an adsorbent dosage of 7 g, mixing time of 20 minutes under a mixing rate of 45–50 revolutions/min, 1 g of oil and provides maximum oil removal efficiency in the present study. Based on the data fit result of the adsorption; the 7 g AP at 20 min (90%) had better oil retention than the 1.5 g (66%), 3 g (77%), and 5 g (82%) AP. The results indicated that the maximum oil adsorption percentage upon increasing the adsorbent dose (1.5 g, 3 g, 5 g, and 7 g peel) was 66-90% for Crude oil, 45-68% for Diesel, 35-56% for Kerosene, and 19-45% for Gas oil at 20 min using 1 gram oil. The results revealed that sorption capacity decreased as the oil got lighter. Increasing the oil dose reduce the adsorption capacity (Crude oil 90-66%, Diesel 64-45%, Kerosene 50-39%, and Gas oil 40-12%). The oil sorption capacities of the AP sorbents reduce gradually from 90-64% after 10 cycles, with about 72%, since the oleophilic nature of the peel surface was affected during the regeneration process. The kinetic data was analyzed for all adsorbent doses. The pseudo-first order kinetic model was found to agree well with then experimental data found. The result showed that AP biosorbent followed pseudo-first order kinetics. According to the results presented, the cheap efficient AP oil spill sorbent could be developed as a potential material to be used in seawater treatment for oil removal. The avocado carbon displayed excellent adsorption properties for the simulated seawater effluents containing oil.

Mussel – Inspired biosorbent combined with graphene oxide for removal of organic pollutants from aqueous solutions

In this work, we develop a mussel-inspired biosorbent combined with graphene oxide for removal of organic dyes in water sources. The composite was prepared via self-polymerization of dopamine in weak alkaline solution containing graphene oxide at ambient condition. Morphological and structural studies revealed that polydopamine has gradually grown to cover the surface of graphene oxide flakes, partially reduced these flakes, and somehow form many grains (size around 20 nm) on the flakes instead of making very large aggregates as usual. The mass ratio between two components of the composite was also investigated to find the optimal one which provides enough surface area (20 m2.g−1) and maintain adhesive sites in order to ensure high-efficiency removal of organic molecules. The adsorption kinetics and isotherms of as-prepared adsorbent towards methylene blue were found to fit well with pseudo-first order kinetics model and Langmuir isotherm. The maximum adsorption capacity (qm) and Langmuir constant (kL) were estimated to be 270 mg.g−1 and 0.49 L. mg−1. The as-prepared bio-sorbent is very promising for remediation of water sources contaminated with cationic organic molecules and heavy metal ions.

Amine Infused Fly Ash Grafted Acrylic Acid/Acrylamide Hydrogel for Carbon Dioxide (CO2) Adsorption and Its Kinetic Analysis.

In most carbon dioxide (CO2) capture processes, chemical absorption using an amine solvent is widely used technology; however, the solvent is prone to solvent degradation and solvent loss which leads to the formation of corrosion. This paper investigates the adsorption performance of amine-infused hydrogels (AIFHs) to increase carbon dioxide (CO2) capture by leveraging the potency of amine absorption and adsorption properties of class F fly ash (FA). The solution polymerization method was used to synthesize the FA-grafted acrylic acid/acrylamide hydrogel (FA-AAc/AAm), which was then immersed in monoethanolamine (MEA) to form amine infused hydrogels (AIHs). The prepared FA-AAc/AAm showed dense matrices morphology with no obvious pore at the dry state but capable of capturing up to 0.71 mol/g CO2 at 0.5 wt% FA content, 2 bar pressure, 30 °C reaction temperature, 60 L/min flow rate, and 30 wt% MEA contents. Cumulative adsorption capacity was calculated and Pseudo-first order kinetic model was used to investigate the CO2 adsorption kinetic at different parameters. Remarkably, this FA-AAc/AAm hydrogel is also capable of absorbing liquid activator that was 1000% more than its original weight. FA-AAc/AAm can be used as an alternative AIHs that employ FA waste to capture CO2 and minimize the GHG impact on the environment.

Chitosan based radiation crosslinked and grafted matrix: An environment friendly adsorbent for dye uptake

The adsorption capacity of [2-(methacryloxy) ethyl] trimethylammonium chloride (MAETC) grafted-crosslinked chitosan (CRChitosan-g-MAETC) using ionizing radiation was evaluated for adsorption of anionic dyes namely Acid Blue-25 (AB25), Reactive Orange-16 (RO16) and Reactive Red-120 (RR120) from manufactured aqueous solutions. Effect of various experimental variables like dye concentration, pH, contact time duration, temperature and adsorption on adsorbent grafted to different extent on adsorption kinetics and on equilibrium adsorption was investigated. To understand the equilibrium adsorption of dyes on the adsorbent the data was fitted into Langmuir, Freundlich and Temkin adsorption isotherms while adsorption kinetics was examined using pseudo-first order, pseudo-second order and intraparticle diffusion kinetic models. It was observed that the adsorption of all the three anionic dyes studied was better explained by the Freundlich model. Adsorption extent of dye varied with number of charge sites on the dye molecule. The adsorption of all the three anionic dyes followed pseudo-second order kinetics. Thermodynamic parameters such as standard enthalpy (ΔHo), standard entropy (ΔSo) and standard free energy (ΔGo) were estimated. The radiation grafted cationic adsorbent showed promising adsorbent properties for removal of anionic dyes.

Amine-Functionalized Natural Rubber/Mesostructured Silica Nanocomposites for Adsorptive Removal of Clofibric Acid in Aqueous Phase

This study is the first report on the synthesis, characterization and application of amine-functionalized mesoporous nanocomposites based on natural rubber (NR) and wormhole-like mesostructured silica (WMS). In comparison with amine-functionalized WMS (WMS-NH2), a series of NR/WMS-NH2 composites were synthesized via an in situ sol-gel method in which the organo-amine group was grafted onto the nanocomposite surface via co-condensation with 3-aminopropyltrimethoxysilane (APS) as the amine-functional group precursor. The NR/WMS-NH2 materials had a high specific surface area (115-492 m2 g-1) and total pore volume (0.14-1.34 cm3 g-1) with uniform wormhole-like mesoporous frameworks. The amine concentration of NR/WMS-NH2 (0.43-1.84 mmol g-1) was increased with an increase in the APS concentration, corresponding to high levels of functionalization with the amine groups of 53-84%. The H2O adsorption-desorption measurement revealed that NR/WMS-NH2 possessed higher hydrophobicity than WMS-NH2. The removal of clofibric acid (CFA), a xenobiotic metabolite of the lipid-lowering drug clofibrate, from the aqueous solution using WMS-NH2 and NR/WMS-NH2 materials was investigated using a batch adsorption experiment. The adsorption was a chemical process in which the pseudo-second order kinetic model expressed the sorption kinetic data better than the pseudo first-order and Ritchie-second kinetic order model. In addition, the CFA adsorption sorption equilibrium data of the NR/WMS-NH2 materials were fitted to the Langmuir isotherm model. The NR/WMS-NH2 with 5% amine loading had the highest CFA adsorption capacity (6.29 mg g-1).

“Gamma Irradiation Synthesis of Carboxymethyl Chitosan-Nanoclay Hydrogel for the Removal of Cr(VI) and Pb(II) from Aqueous Media”

Hydrogel composites comprised of N,O carboxymethyl chitosan crosslinked with different weight ratios of acrylic acid and fabricated with nanoclay particle were prepared via gamma irradiation at 25 kGy irradiation dose. The prepared composites were coded as CsAA1Cl, CsAA2Cl and CsAA3Cl based on the weight ratio of acrylic acid to the chitosan derivative. The claimed hydrogels were characterized by FTIR, TGA and XRD. The TGA data implied that the incorporation of clay nanoparticles enhanced the thermal stability of the composites; the decomposition temperature increased up to 500 °C for CsAA3Cl. Three AFM outcomes were used to compare the surface features of the samples; topography, height and surface roughness. The topography data reveals that the nanoclay particles incorporated in CsAA3Cl are intercalated and exfoliated. Then, the optimized sorbent (CsAA3Cl) was investigated as green sorbents for chromium (VI) and lead (II). The data revealed that CsAA3Cl displayed maximum removal performance towards both lead and chromium with removal efficiencies 125 mg/g and 205 mg/g respectively at the optimum application conditions within 90 min only. Also, it was found that the optimum pH value was 9 for chromium and 8 for lead. The data proved that the adsorption of both cations followed pseudo-first order kinetic model. The prepared composites showed acceptable metal uptake capacity at three successive cycles.Graphical

Adsorptive removal of crystal violet dye by Azadirachta indica (neem) sawdust: A low-cost bio-sorbent

The potentiality of Azadirachta indica sawdust as a cost-effective natural adsorbent for adsorptive elimination of a cationic dye crystal violet from aqueous emulsion was investigated. Because sawdust is plentiful and low-cost by-product. Additionally, sawdust can be composted to replace the regeneration stage that other adsorbents like activated carbon requires. Kinetic and isotherm analyses were conducted under variable experimental conditions including adsorbent dose, dye concentration, contact time, pH, and temperature. A maximum adsorption capacity of 8.264 mgg−1 was obtained at optimized conditions of 2.5 gl−1, 100 mgl−1 30 min, 6, and 25 °C for adsorbent dose, adsorbate, contact time, pH and temperature. The nature of any probable interaction between adsorbent and crystal violet was analyzed by FTIR technique, to investigate the type of functional groups in saw dust responsible for dye binding process. The FTIR studies showed the existence of C-H, C=O, C-O, C=C, O-H, C-N, -COO- and Si-O functional groups. It was noted that the sorption kinetics followed a pseudo-second order kinetic model after the sorption was examined using pseudo-first and pseudo-second order kinetic models. The magnitude of dye removal increased with increase of adsorbent dose and slightly decreased with increase in adsorbate concentration. Up to 45 °C temperature, there was no significant impact on sorption only 2–5% higher than the 25 °C and 35 °C treatments. The Langmuir isotherm model provided a good representation of the equilibrium data in aqueous solutions. The adsorption capability of crystal violet onto the sawdust of Azadirachta indica was found to be as high as 8.278 mgg−1, at pH 6.0, temperature 25 °C, and at equilibrium time of 60 min after applying Langmuir isotherm equation. Azadirachta indica sawdust seems to be a very promising adsorbent for the removal of crystal violet from aqueous solution.

Parametric and kinetic studies of activated sludge dewatering by cationic chitosan-like bioflocculant BF01314 produced from Citrobacter youngae

Bacterial strains belonging to Citrobacter spp. were reported to produce polysaccharides consisting of N-acetylglucosamine and glucosamine like chitosan, with high flocculation activity. In this work, the flocculation dewatering performance of activated sludge conditioned by a novel cationic chitosan-like bioflocculant (BF) named BF01314, produced from Citrobacter youngae GTC 01314, was evaluated under the influences of flocculant dosage, pH, and temperature. At BF dosage as low as 0.5 kg/t DS, the sludge dewaterability was significantly enhanced in comparison to the raw (untreated) sludge, featuring well-flocculated characteristic (reduction in CST from 22.0 s to 9.4 s) and good sludge filterability with reduced resistance (reduction in SRF by one order from 7.42 × 1011 to 9.59 × 1010 m/kg) and increased compactness of sludge (increase in CSC from 15.2 to 23.2%). Besides, the BF demonstrated comparable high sludge dewatering performance within the pH range between 2 and 8, and temperature range between 25 °C and 80 °C. Comparison between the BF, the pristine chitosan and the commercial cationic copolymer MF 7861 demonstrated equivalent performance with enhanced dewaterability at the dosage between 2.0 and 3.0 kg/t DS. Besides, the BF demonstrated strong flocculation activity (>99%) when added to the sludge suspension using moderate to high flocculation speeds (100–200 rpm) with at least 3-min mixing time. The BF's reaction in sludge flocculation was best fitted with a pseudo first-order kinetic model. Electrostatic charge patching and polymer bridging mechanisms are believed to be the dominant mechanistic phenomena during the BF's sludge conditioning process (coagulation-flocculation).

Bioremediation of arsenic using magnetic NdFeO3 nanoparticles functionalized with microbial biofilm

Magnetic support of NdFeO3 was synthesized to solve the problem of inorganic arsenic species contamination in water. NdFeO3 nanoparticles showed an adsorption capacity of 54.2 and 156.0 mg/g, for As (III) and As (V) respectively. The adsorption isotherms showed a good adsorption performance at pH 3 and 9 for both As species, showing more adsorption capacity for As (V) than As (III). Adsorption of As (III) on NdFeO3 showed a good fit with a pseudo-first order kinetic model and with the Avrami model. The reaction was endothermic, spontaneous, and exhibited increasing entropy. Looking to improve the arsenical remediation, the NdFeO3 was associated with the biofilm from Microbacterium oxydans AE038–20. The biofilm attached to the nanoparticles showed good stability and was characterized by TGA, SEM, and FTIR. Thus, a magnetic nanocomposite (mNFO@biofilm) was successfully fabricated and used as an adsorbent for the simultaneous removal of As (III) and As (V). mNFO@biofilm displayed a remarkable adsorption performance for both As (III) and As (V) removal at acidic and basic pH (3 and 9). The microbial biofilm attached to nanoparticles of NdFeO3 facilitated the remotion process showing an arsenic adsorption capacity of 84.80%. Additionally, the mNFO@biofilm improved the arsenical removal not only by the best adsorption than the nanoparticles alone but also was able to oxidize the As (III) to As (V). Finally, the NdFeO3 nanoparticles were recovered by removing the biofilm by heating. Thus, the recovery and potential reusability of these nanoparticles improved their application for arsenic water remediation.

Kinetic modeling of advanced starch oxidation with ozone in basic solutions

ABSTRACT The growing use of ozone (O3) in the last years to clean and enhance the physicochemical properties of starches, widely used as additives in food, beverage, and pharmaceutical industries, calls for a better understanding of their oxidation process. High pH, however, decomposes O3 rapidly, forming highly-oxidant radicals, thus increasing the complexity of the reaction system. In this study, a kinetic model for the ozonation reaction of starch in an alkaline medium was developed and experimentally validated. Firstly, the concentration of hydroxyl radicals (●OH) over the reaction time is evaluated through the degradation of pCBA (a probe compound) to later evaluate and model the oxidation process of starch based on Chemical Oxygen Demand (COD) measurements. By using a semi-batch reactor containing alkaline solutions at pH = 13, different O3 concentrations (0–42.30 g/Nm3) and temperatures (20–60 °C), a pseudo first-order kinetic model was proposed to model the pCBA-ozone reaction. This model estimates the ●OH formation, being [●OH] constant and proportional to the O3 continuous dose. Therefore, under the conditions studied, ●OH is a non-limiting reactant independent of temperature. The activation energy was estimated at 14.2 ± 2.1 and 14.5 ± 0.6 KJ/mol for 21.15 and 42.30 gO3/Nm3, respectively. Then, COD data were used to propose a kinetic model for ozone-starch oxidation in alkaline media, where besides O3 concentration and temperature, starch concentration (600–1700 mg/L) was also varied. According to the results, higher temperatures and longer reaction times resulted in a greater COD reduction, being it more pronounced at lower initial starch concentration. The activation energy of the ozone radicals-starch reaction was estimated at 8.1 ± 0.4 KJ/mol, being significantly lower than those reported for the reaction between pCBA and ●OH.

Adsorption of As and Pb by Stone Powder/Chitosan/Maghemite Composite Beads (SCM Beads): Kinetics and Column Study

Adsorption kinetics of As and Pb onto composite beads synthesized with stone powder, chitosan, and maghemite (SCM beads) with weight ratio of 1:1:0.5 were investigated in batch mode. Several kinetic models such as pseudo-first order kinetic model (PFOKM), pseudo-second order kinetic model (PSOKM), two compartment first order kinetic model (TCFOKM), and modified two compartment first order kinetic model (MTCFOKM) were utilized to analyze the kinetics. Although the beads had low specific surface area and pore volume, MTCFOKM, one of two compartment models, could predict the most accurately because the As and Pb were adsorbed onto at least two kinds of adsorption sites such as functional groups in chitosan and Fe in maghemite. In MTCFOKM, both the fast adsorption fraction (f1’) and the fast adsorption constant (k1’) for Pb were higher than those for As. Therefore, the equilibrium time (teq) for Pb adsorption was shorter than that for As adsorption, indicating that Pb adsorption was more affinitive than As adsorption onto SCM beads (especially maghemite). Column study with a bed column reactor packed with the SCM beads was also conducted. For column study, the effect of flow rate and pore volume on removal efficiency of As and Pb was also investigated. Three models such as the Thomas, Adams-Bohart (A-B), and Yoon-Nelson (Y-N) models were used to fit the column experimental data to analyze the breakthrough curves and the saturation time. Both Thomas and Y-N models were most appropriate. Conclusively, the SCM beads are suitable for adsorption treatment of As and Pb from contaminated groundwater and are particularly effective in Pb removal.

Efficiency and Mechanism of O3-SBBR Combined Process for Advanced Treatment of Biochemical Effluent from Printing and Dyeing Industrial Park

With the aim of addressing the difficult problem of biodegradable organic nitrogen in biochemical effluent of a printing and dyeing industrial park, the combined ozonation-sequencing batch biofilm reactor (O3-SBBR) process was used for advanced treatment. The influencing factors and degradation kinetics were analyzed; quenching experiments were carried out; and the types of free radicals, succinate dehydrogenase activity, and denitrification function genes were determined. The results showed that the suitable ozonation condition was pH 8.0-8.5, O3 concentration was approximately 35.0 mg·L-1, O3 dosage was approximately 100.0 mg·L-1, and reaction time was 90.0-120.0 min. Organic nitrogen in the biochemical effluent by ozonation conformed to the pseudo first-order kinetic model, and the maximum rate constant k was 0.01035 min-1 (experimental conditions:pH 8.0, ozone dosage 150.0 mg·L-1, and ozone concentration 35.0 mg·L-1). Ozonation significantly improved the denitrification performance of the sequencing biofilm batch reactor (SBBR), and the denitrification efficiency increased from 19.8% (SBBR) to 32.9% (O3-SBBR). Ozonation could convert organic nitrogen and organic substances with strong toxicity and difficult biological utilization into small molecular substances with low toxicity and biodegradability. The abundance of functional genes (nirS, nirK, and nor) in the O3-SBBR combined process was significantly higher than that in the single SBBR, which further confirmed that ozonation could improve the nitrogen removal performance of SBBR. The operation cost of the combined process was 0.74-1.07 yuan·m-3, with good technical economy. This study provided a basis for the application of the O3-SBBR combined process in the advanced treatment of biochemical effluent in printing and dyeing industrial parks.

H2O2 activation over Cu-Schiff bases nanozyme for the removal of amlodipine: Kinetics, mechanism and toxicity evaluation

Artificial nanozyme is a promising alternative approach to replace natural enzyme and promote their industrialization. For designing artificial enzymes, the structure of the ligand is one of the important factors which needs to be considered. Schiff bases as special donor ligands could effectively stabilize active metal ions, endowing them playing important roles in the field of artificial enzymes. Herein, we focused on constructing a Schiff base metal complex with peroxidase-like activities to achieve efficient activation of hydrogen peroxide (H2O2) for the removal of amlodipine (AML). Polydopamine (PDA) and 3, 5-dibromosalicylaldehyde (DBSA) were used as raw materials to synthesize the Schiff base (DPDA), and Cu2+ is used for the coordination reaction to synthesize the Schiff base metal complex (Cu@SB). Our results demonstrated the prepared Cu@SB effectively activated H2O2 to degrade AML, and the removal of AML followed a pseudo first-order kinetic model. Electron paramagnetic resonance (EPR) tests and quenching tests showed •OH and 1O2 were responsible for removing AML. X-ray photoelectron spectroscopy (XPS) analysis implied the redox reaction of Cu(I)/Cu(II) participated in the catalytic process. Three major transformation pathways including dehydrogenation, oxidative deamination and hydroxylation were proposed based on density functional theory (DFT) calculations and LC-MS/MS analysis. Moreover, it was discovered that the toxicities of most intermediates were lower than AML. Overall, this study provides new insights into constructing peroxidase-like catalysts used for the efficient activation of H2O2 to remove emerging organic pollutants in water, broadening the application of Schiff bases in wastewater treatment.

A Modern Computer Application to Model Rare Earth Element Ion Behavior in Adsorptive Membranes and Materials

The following paper offers a modern REE 1.0 computer application designed to model the behavior of REE ions in adsorptive materials and membranes. The current version of the application is based on several models, such as the Lagergren pseudo-first order, pseudo-second-order and Elovich kinetic models, and the intraparticle diffusion model, the diffusion-chemisorption model, and the Boyd model. The application has been verified on a sample of four different types of adsorptive materials and membranes. The proposed application allowed the analysis of kinetics, but also the mechanisms of the adsorption process, especially those responsible for the rate-determining steps. It was found that Lagergren pseudo-second-order kinetic model was the best-fit model to describe the adsorption behavior of REE ions onto the novel materials and membranes. Other models determined the process of chemisorption was in force for the analyzed cases, and the mechanisms controlling the adsorption processes are diffusion-chemisorption and adsorption is mostly controlled by film diffusion. Additionally, characteristic parameters, such as qe designated from two different models, showed very similar values, which indicates the correctness of the analysis.

Synthesis of Bi2O3 NPs with polyethylene glycol and investigation of photodegradation of phenazopyridine in aqueous solution

The synthesis of Bi2O3 by a simple chemical route in the presence of polyvinylpyrrolidone (PP) as surfactant was studied. The sample was characterized by XRD, FTIR, and DRS techniques. Its pHpzc was estimated about 9.5. Crystallite size of the as-synthesized sample was estimated about 45 and 14 nm by the Scherrer and Williamson-Hall models, respectively. Band gap energy was estimated about 2.98 eV using the adsorption edge wavelength, while by using the Kubelka-Munk theory Eg-values of 3.21, 3.13, 3.27, and 3.24 eV were obtained for n-values of 2, 1/2, 3/2, and 3, respectively. The photocatalytic performance of the Bi2O3 NPs was evaluated against phenazopyridine as a model pollutant. Experimental optimized parameters were as adsorbent dosage = 0.7 g/L, contact time = 60 min, pH 7, illumination time: 60 min, CPP: 20 ppm. The photocatalytic kinetics model obeyed the pseudo-first order kinetic model.

Adsorptive desulfurization of model and real fuel via wire-, rod-, and flower-like Fe3O4@MnO2@activated carbon made from palm kernel shells as newly designed magnetic nanoadsorbents

The removal of organic sulphur from liquid fuel via applicable and cheap processes is one of the most challenging energy issues worldwide. Adsorptive desulfurization (ADS) processes can address this issue if highly effective magnetic nanoadsorbents with favourable textural properties are used. In this work, activated carbon produced from palm kernel shells was decorated with wire-, rod- and flower-like magnetic MnO2 by a hydrothermal route to produce reusable magnetic nanoadsorbents with tunable pore volume and pore diameter. The magnetic nanoadsorbents labelled Fe3O4@MnO2-w@AC, Fe3O4@MnO2-r@AC and Fe3O4@MnO2-f@AC were characterized using state-of-the-art spectroscopic techniques and used for sulphur removal from model and real fuels. The results revealed that the prepared magnetic nanoadsorbents had suitable oxygen functionalities, porous morphology and specific surface area of 480 for wire, 312 for rod, and 340 m2/g for flower-like magnetic nanoadsorbents. The newly-designed magnetic nanoadsorbents exhibited superior sulphur removal efficiency at 100 min contact time, 35 °C adsorption temperature, and 0.4 g adsorbent dose per 40 mL of model or real fuel. Among them, a wire-like magnetic nanoadsorbent showed 99 % sulphur removal from model fuel with 530 ppm sulphur content as DBT, 97.6 % and 90 % sulphur removal from commercial kerosene and diesel fuels with 430 and 1050 ppm sulphur content, respectively. The adsorption kinetics, isotherms and thermodynamics disclosed that adsorption of organic sulphur follows the pseudo first-order kinetic model, was an exothermic, and diffusion-controlled process. The magnetic properties enabled the nanoadsorbents to be recovered more easily and reused at least five times.

Electron beam degradation of the cardiovascular drug salbutamol: Mechanisms and degradation pathways

With the increasing incidence and mortality of cardiovascular diseases, high consumption of the cardiovascular drug salbutamol (SAL) has made this compound an emerging pollutant in natural water and a challenge for traditional wastewater treatment. In this paper, an efficient advanced oxidation process was used to degrade SAL by electron beam (EB) irradiation. The results revealed that 100 mg L−1 of SAL could be nearly completely removed (95.1%) at 10 kGy and the degradation kinetic well followed pseudo first-order kinetic model. Different factors, including pH, inorganic ions and water matrix, had varying effects on the degradation of SAL owing to their important influence on the formation of reactive species in the aqueous solution. And it was found that eaq− played a major role in the degradation of SAL parent. Moreover, the addition of K2S2O8 (20 mM) increased the SAL mineralization rate from 2.9% to 64.2%, suggesting that oxidation free radicals could greatly improve the mineralization rate of SAL. Combining with the theoretical calculations and determined degradation by-products, four possible degradation pathways of SAL by EB irradiation were proposed, including H•, •OH and eaq− all participated in the degradation of SAL. Finally, toxicity evaluation suggested that the toxicity of SAL aqueous solution reduced after EB irradiation, indicating that it is an effective method to degrade SAL.